package com.dmall.tries;

/**
 * 基于数组的Trie
 * @author xiao1.wang@dmall.com
 * @date 2019-08-25 16:21:01
 */
public class Trie3 {

    private class Node {

        public boolean isWord;
        public Node[] next;

        public Node(boolean isWord) {
            this.isWord = isWord;
            next = new Node[26];
        }

        public Node() {
            this(false);
        }
    }

    private Node root;
    private int size;

    public Trie3() {
        root = new Node();
        size = 0;
    }

    /**
     * 获得Trie中存储的单词数量
     * @return
     */
    public int getSize() {
        return size;
    }

    /**
     * 向Trie中添加一个新的单词word
     * @param word
     */
    public void add(String word) {

        Node cur = root;
        for(int i = 0 ; i < word.length() ; i ++) {
            char c = word.charAt(i);
            if(cur.next[c - 'a'] == null) {
                cur.next[c - 'a'] = new Node();
            }
            cur = cur.next[c - 'a'];
        }

        if(!cur.isWord) {
            cur.isWord = true;
            size ++;
        }
    }

    /**
     * 查询单词word是否在Trie中
     * @param word
     * @return
     */
    public boolean contains(String word) {

        Node cur = root;
        for(int i = 0 ; i < word.length() ; i ++) {
            char c = word.charAt(i);
            if(cur.next[c-'a'] == null) {
                return false;
            }
            cur = cur.next[c-'a'];
        }
        return cur.isWord;
    }
}
